128 



in more exposed situations, and the bollworm is thus able to develop 

 with comparative freedom from these important natural checks. 



In the case of many insects affecting staple crops their best control 

 is often to be found in the adoption of some change in farm practice 

 that will take advantage of some peculiarity in the life and habits of 

 the pest. Such changes are usually quite in line with better farming, 

 and involve no extra outlay of labor and money not warranted for 

 other reasons than those of insect control. The bollworm falls easily 

 into this class of insects, and the means which are of most importance 

 in avoiding injury consist in certain changes in agricultural practice 

 which are in themselves desirable, aside from their influence on the 

 pest. 



Attention has elsewhere been called to the relation of the farm- 

 ing methods in vogue to bollworm injury to cotton. Experiments dur- 

 ing the past two years indicate that by improved cultural methods 

 much may bo done to insure a crop of cotton, even during years of 

 severe bollworm injury. Detailed results of field experiments have 

 been given in Farmers' Bulletins Nos. 191 and 212, to which the reader 

 is referred. The value of the so-called cultural method lies in the 

 fact that cotton is not attacked in force until the field corn of the sur- 

 rounding country, the favorite food of the bollworm, has begun to 

 yellow and ripen and is no longer attractive to the moths for egg- 

 laying purposes. The moths, therefore, concentrate in the cotton 

 fields, obtaining their food from the nectaries on the squares and 

 flowers of the cotton plant, and on these latter they deposit the bulk of 

 their eggs. This time of migration to cotton will vary somewhat, 

 depending on the relative earliness of surrounding corn, but will aver- 

 age, one year with another, about the 1st of August, for the central 

 and northern parts of the cotton belt. 



Another fact to be mentioned in this connection is the comparative 

 immunity of the larger and maturer cotton bolls to attack b}^ boll- 

 worms, as compared with the smaller bolls and squares. This is indi- 

 cated on page 72. These two circumstances in the natural history of 

 the insect permit, by the use of improved cultural methods, of the 

 production of a fair crop of cotton ahead of danger from bollworm 

 injury in August. 



The importance of the earl}^ production of a maximum number of 

 advanced bolls is therefore evident, and the cultural method involves 

 the employment of all such means as 'will contribute to that end, 

 such as — 



(1) Thorough plowing of land in the fall to destroy as man}^ hiber- 

 nating pupae as possible. 



(2) The use of seed of earl3^-fruiting varieties. 



(3) The use of fertilizers to hasten and increase fruit production. 



(4) Earl}^ planting in the spring. 



(5) Early and thorough cultivation. 



